The present invention relates to the field of non-viral transfection of nucleic acids. The term transfection generally means the introduction of foreign substances into cells. The present invention relates to a method for the transfection of cells with the help of at least one protein which is capable of forming nucleoprotein filaments. The invention also relates to a transfection agent which contains a nucleoprotein filament (NPF) which is formed from at least one nucleic acid to be transfected and at least one protein which is capable of forming nucleoprotein filaments. In addition, the present invention relates to the use of the transfection agent according to the invention, a corresponding pharmaceutical formulation, in particular for use in gene therapy, a kit for the transfection of cells with nucleic acids and particular methods which use the transfection agent according to the invention.